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<?php
/**
* This is a PHP library that handles calling reCAPTCHA.
* - Documentation and latest version
* {@link http://code.google.com/apis/recaptcha/docs/php.html}
* - Get a reCAPTCHA API Key
* {@link https://www.google.com/recaptcha/admin/create}
* - Discussion group
* {@link http://groups.google.com/group/recaptcha}
*
* Copyright (c) 2007 reCAPTCHA -- {@link http://www.google.com/recaptcha}
* AUTHORS:
* Mike Crawford
* Ben Maurer
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* @package moodlecore
* @copyright (c) 2007 reCAPTCHA -- {@link http://www.google.com/recaptcha}
*/
/**
* The reCAPTCHA server URL's
*/
define("RECAPTCHA_API_SERVER", "http://www.google.com/recaptcha/api");
define("RECAPTCHA_API_SECURE_SERVER", "https://www.google.com/recaptcha/api");
define("RECAPTCHA_VERIFY_SERVER", "www.google.com");
/**
* Encodes the given data into a query string format
* @param $data - array of string elements to be encoded
* @return string - encoded request
*/
function _recaptcha_qsencode ($data) {
$req = "";
foreach ( $data as $key => $value )
$req .= $key . '=' . urlencode( $value ) . '&';
// Cut the last '&'
$req=substr($req,0,strlen($req)-1);
return $req;
}
/**
* Submits an HTTP POST to a reCAPTCHA server
*
* @global object
* @param string $host
* @param string $path
* @param array $data
* @param int port
* @return array response
*/
function _recaptcha_http_post($host, $path, $data, $port = 80, $https=false) {
global $CFG;
$protocol = 'http';
if ($https) {
$protocol = 'https';
}
require_once $CFG->libdir . '/filelib.php';
$req = _recaptcha_qsencode ($data);
$headers = array();
$headers['Host'] = $host;
$headers['Content-Type'] = 'application/x-www-form-urlencoded';
$headers['Content-Length'] = strlen($req);
$headers['User-Agent'] = 'reCAPTCHA/PHP';
$results = download_file_content("$protocol://" . $host . $path, $headers, $data, false, 300, 20, true);
if ($results) {
return array(1 => $results);
} else {
return false;
}
}
/**
* Gets the challenge HTML (javascript and non-javascript version).
* This is called from the browser, and the resulting reCAPTCHA HTML widget
* is embedded within the HTML form it was called from.
*
* @global object
* @param string $pubkey A public key for reCAPTCHA
* @param string $error The error given by reCAPTCHA (optional, default is null)
* @param boolean $use_ssl Should the request be made over ssl? (optional, default is false)
* @return string - The HTML to be embedded in the user's form.
*/
function recaptcha_get_html ($pubkey, $error = null, $use_ssl = false) {
global $CFG, $PAGE;
$recaptchatype = optional_param('recaptcha', 'image', PARAM_TEXT);
if ($pubkey == null || $pubkey == '') {
die ("To use reCAPTCHA you must get an API key from <a href='https://www.google.com/recaptcha/admin/create'>https://www.google.com/recaptcha/admin/create</a>");
}
if ($use_ssl) {
$server = RECAPTCHA_API_SECURE_SERVER;
} else {
$server = RECAPTCHA_API_SERVER;
}
$errorpart = "";
if ($error) {
$errorpart = "&amp;error=" . $error;
}
require_once $CFG->libdir . '/filelib.php';
$html = download_file_content($server . '/noscript?k=' . $pubkey . $errorpart, null, null, false, 300, 20, true);
preg_match('/image\?c\=([A-Za-z0-9\-\_]*)\"/', $html, $matches);
$challenge_hash = $matches[1];
$image_url = $server . '/image?c=' . $challenge_hash;
$strincorrectpleasetryagain = get_string('incorrectpleasetryagain', 'auth');
$strenterthewordsabove = get_string('enterthewordsabove', 'auth');
$strenterthenumbersyouhear = get_string('enterthenumbersyouhear', 'auth');
$strgetanothercaptcha = get_string('getanothercaptcha', 'auth');
$strgetanaudiocaptcha = get_string('getanaudiocaptcha', 'auth');
$strgetanimagecaptcha = get_string('getanimagecaptcha', 'auth');
$return = html_writer::script('', $server . '/challenge?k=' . $pubkey . $errorpart);
$return .= '<noscript>
<div id="recaptcha_widget_noscript">
<div id="recaptcha_image_noscript"><img src="' . $image_url . '" alt="reCAPTCHA"/></div>';
if ($error == 'incorrect-captcha-sol') {
$return .= '<div class="recaptcha_only_if_incorrect_sol" style="color:red">' . $strincorrectpleasetryagain . '</div>';
}
if ($recaptchatype == 'image') {
$return .= '<span class="recaptcha_only_if_image">' . $strenterthewordsabove . '</span>';
} elseif ($recaptchatype == 'audio') {
$return .= '<span class="recaptcha_only_if_audio">' . $strenterthenumbersyouhear . '</span>';
}
$return .= '<input type="text" id="recaptcha_response_field_noscript" name="recaptcha_response_field" />';
$return .= '<input type="hidden" id="recaptcha_challenge_field_noscript" name="recaptcha_challenge_field" value="' . $challenge_hash . '" />';
$return .= '<div><a href="signup.php">' . $strgetanothercaptcha . '</a></div>';
// Disabling audio recaptchas for now: not language-independent
/*
if ($recaptchatype == 'image') {
$return .= '<div class="recaptcha_only_if_image"><a href="signup.php?recaptcha=audio">' . $strgetanaudiocaptcha . '</a></div>';
} elseif ($recaptchatype == 'audio') {
$return .= '<div class="recaptcha_only_if_audio"><a href="signup.php?recaptcha=image">' . $strgetanimagecaptcha . '</a></div>';
}
*/
$return .= '
</div>
</noscript>';
return $return;
}
/**
* A ReCaptchaResponse is returned from recaptcha_check_answer()
*
* @package moodlecore
* @copyright (c) 2007 reCAPTCHA -- {@link http://www.google.com/recaptcha}
*/
class ReCaptchaResponse {
var $is_valid;
var $error;
}
/**
* Calls an HTTP POST function to verify if the user's guess was correct
* @param string $privkey
* @param string $remoteip
* @param string $challenge
* @param string $response
* @return ReCaptchaResponse
*/
function recaptcha_check_answer ($privkey, $remoteip, $challenge, $response, $https=false)
{
if ($privkey == null || $privkey == '') {
die ("To use reCAPTCHA you must get an API key from <a href='https://www.google.com/recaptcha/admin/create'>https://www.google.com/recaptcha/admin/create</a>");
}
if ($remoteip == null || $remoteip == '') {
die ("For security reasons, you must pass the remote ip to reCAPTCHA");
}
//discard spam submissions
if ($challenge == null || strlen($challenge) == 0 || $response == null || strlen($response) == 0) {
$recaptcha_response = new ReCaptchaResponse();
$recaptcha_response->is_valid = false;
$recaptcha_response->error = 'incorrect-captcha-sol';
return $recaptcha_response;
}
$response = _recaptcha_http_post(RECAPTCHA_VERIFY_SERVER, "/recaptcha/api/verify",
array (
'privatekey' => $privkey,
'remoteip' => $remoteip,
'challenge' => $challenge,
'response' => $response
),
$https
);
$answers = explode ("\n", $response [1]);
$recaptcha_response = new ReCaptchaResponse();
if (trim ($answers [0]) == 'true') {
$recaptcha_response->is_valid = true;
}
else {
$recaptcha_response->is_valid = false;
$recaptcha_response->error = $answers [1];
}
return $recaptcha_response;
}
/**
* gets a URL where the user can sign up for reCAPTCHA. If your application
* has a configuration page where you enter a key, you should provide a link
* using this function.
* @param string $domain The domain where the page is hosted
* @param string $appname The name of your application
*/
function recaptcha_get_signup_url ($domain = null, $appname = null) {
return "https://www.google.com/recaptcha/admin/create?" . _recaptcha_qsencode (array ('domains' => $domain, 'app' => $appname));
}
function _recaptcha_aes_pad($val) {
$block_size = 16;
$numpad = $block_size - (strlen ($val) % $block_size);
return str_pad($val, strlen ($val) + $numpad, chr($numpad));
}
/* Mailhide related code */
function _recaptcha_aes_encrypt($val,$ky) {
if (! function_exists ("mcrypt_encrypt")) {
die ("To use reCAPTCHA Mailhide, you need to have the mcrypt php module installed.");
}
$mode=MCRYPT_MODE_CBC;
$enc=MCRYPT_RIJNDAEL_128;
$val=_recaptcha_aes_pad($val);
return mcrypt_encrypt($enc, $ky, $val, $mode, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0");
}
function _recaptcha_mailhide_urlbase64 ($x) {
return strtr(base64_encode ($x), '+/', '-_');
}
/* gets the reCAPTCHA Mailhide url for a given email, public key and private key */
function recaptcha_mailhide_url($pubkey, $privkey, $email) {
if ($pubkey == '' || $pubkey == null || $privkey == "" || $privkey == null) {
die ("To use reCAPTCHA Mailhide, you have to sign up for a public and private key, " .
"you can do so at <a href='http://www.google.com/recaptcha/mailhide/apikey'>http://www.google.com/recaptcha/mailhide/apikey</a>");
}
$ky = pack('H*', $privkey);
$cryptmail = _recaptcha_aes_encrypt ($email, $ky);
return "http://www.google.com/recaptcha/mailhide/d?k=" . $pubkey . "&c=" . _recaptcha_mailhide_urlbase64 ($cryptmail);
}
/**
* gets the parts of the email to expose to the user.
* eg, given johndoe@example,com return ["john", "example.com"].
* the email is then displayed as john...@example.com
*/
function _recaptcha_mailhide_email_parts ($email) {
$arr = preg_split("/@/", $email );
if (strlen ($arr[0]) <= 4) {
$arr[0] = substr ($arr[0], 0, 1);
} else if (strlen ($arr[0]) <= 6) {
$arr[0] = substr ($arr[0], 0, 3);
} else {
$arr[0] = substr ($arr[0], 0, 4);
}
return $arr;
}
/**
* Gets html to display an email address given a public an private key.
* to get a key, go to:
*
* http://www.google.com/recaptcha/mailhide/apikey
*/
function recaptcha_mailhide_html($pubkey, $privkey, $email) {
$emailparts = _recaptcha_mailhide_email_parts ($email);
$url = recaptcha_mailhide_url ($pubkey, $privkey, $email);
return htmlentities($emailparts[0]) . "<a href='" . htmlentities ($url) .
"' onclick=\"window.open('" . htmlentities ($url) . "', '', 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=500,height=300'); return false;\" title=\"Reveal this e-mail address\">...</a>@" . htmlentities ($emailparts [1]);
}
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